1. Field of the Invention
The present invention relates to a mobile radio network, and in particular to a GSM Standard (Global System for Mobile communication) network;
2. Description of Releted Art
A GSM a network comprises a large number of mutually adjacent and overlapping radio cells which extend over the entire network area. Located in each radio cell is a base transmitting and receiving station via which wire-free communication takes place with the subscribers' mobile radio stations (mobile radio telephone, car telephone). The information is in this case transmitted digitally, in coded form. A plurality of base stations are in turn driven by a so-called base station controller, of which there are a number in the mobile radio network. They control, inter alia, the switching of communication from one radio cell to an adjacent radio cell. The individual base station controllers are now, for their part, connected to a higher-level mobile radio center--the so-called mobile switching center (MSC). This mobile radio center is used, inter alia, as an interface between the mobile radio network and the wire-based telecommunications network.
Within the GSM mobile radio network, a subscriber identifies himself to the network with the aid of a smart card which is inserted into the mobile radio station. The subscriber identification and mobile radio station are thus de-coupled, to allow high flexibility. In order to prevent misuse of the card, the use of this card is linked to the entry of a personal identification number (PIN). This number is stored in the smart card, a PIN that has been entered being compared in the processor chip of the card with the PIN stored there. In the GSM Standard, this subscriber smart card is called a SIM card (Subscriber Identity Module).
In the so-called initialization and personality steps, which are carried out by the SIM card manufacturer and/or by the card issuing authority (for example the network operator, service provider), application-specific and/or personal data and programs are respectively loaded in the non-volatile EEPROM memory of the SIM card.
Within a GSM network it is possible to send short messages to the SIM card, which are then stored there and can be displayed on the mobile radio telephone display (e.g GSM 11.11 and GSM 3.40). After being displayed these short messages are deleted this service is referred to as the normal short message service. Short messages can be sent via a mobile radio center both to all subscribers or to a specific group of subscribers, and from subscriber A to subscriber B.
European patent 0562890 describe the use of the short message service for reconfiguration of a SIM card via the radio link, for example adding to or overwriting a telephone number directory stored in the SIM card. This so-called update short message (reconfiguration short message) has a different quality to that of a normal short message, where a message is stored only briefly and may be displayed on the mobile radio station display.
The object of the present invention therefore is to provide an efficient and reliable method by which a SIM card can distinguish between an update short message and a normal short message.